.

Fig. 16.--Arcyria Cookei, Massee.

Fig. 17.--Arcyria minor, Schw.

Fig. 18.--Heterotrichia Gabriellae, Massee. (After Massee.)

Fig. 19.--Hemiarcyria plumosa, Morgan.

Fig. 20.--Hemiarcyria funalis, Morgan.

Fig. 21.--Calonema aureum, Morgan.

Fig. 22.--Trichia fallax, Pers.

Fig. 23.--Trichia scabra, Rost.

Fig. 24.--Oligonema flavidum, Peck.

NOTE.--Each figure exhibits the sporangium as it appears magnified about
100 diameters, and the capillitium and spores magnified about 500
diameters.

[Illustration: The Journal of the Cin. Soc. Natural History.

VOL. XVI. PLATE I.]

* * * * *

THE MYXOMYCETES OF THE MIAMI VALLEY, OHIO.

BY A. P. MORGAN.

Third Paper.

(Read February 6, 1894.)

ORDER VI. STEMONITACEAE.

Sporangia globose or ovoid to oblong and cylindrical, stipitate; the
wall very thin and fragile, soon disappearing. Stipe tapering upward and
continued within the sporangium as a more or less elongated columella.
Capillitium of slender brown threads, arising from numerous points of
the columella, repeatedly branching and usually anastomosing to form a
network, persistent and rigidly preserving the outline of the
sporangium. Spores globose, brown or violaceous.

This order is readily distinguished by the brown persistent capillitium,
arising from a lengthened columella, and rigidly maintaining the form of
the sporangium.

Table of Genera of Stemonitaceae.

_A. Stipe and columella brown or black._

_a. The columella scarcely reaching the center of the sporangium._

1. CLASTODERMA. Threads of the capillitium forking several times, but
not combined into a network.

2. LAMPRODERMA. Threads of the capillitium branching and anastomosing to
form a network.

_b. The columella extending beyond the center of the sporangium._

3. COMATRICHA. Threads of the capillitium forming only an interior
network, attaining the wall by numerous more or less elongated free
extremities.

4. STEMONITIS. Threads of the capillitium forming an interior network of
large meshes and a superficial network of smaller meshes.

5. ENERTHENEMA. Threads of the capillitium pendent from a discoid
membrane at the apex of the columella.

_B. Stipe and columella white or yellowish._

6. DIACHAEA. Threads of the capillitium branching and anastomosing to
form a network.

I. CLASTODERMA, Blytt. Sporangium regular, globose, stipitate;